Study On Adsorption Of Organic Pollutants And Heavy Metals From Aqueous Solution On Modified Bentonite

As a result of the rapid development of industry, more and more organic pollutantsand heavy metals have been released into into water environment, which results in thatwater environment pollution is getting more and more serious.The adsorption is one ofthe effective methods that could remove organic pollutants and heavy metals in water.Based on the summary about the application of modified bentoite, the long carbon chaincationic CTMAB, short carbon chain cationic TMAB, new cationic L-CsyH, carbon-nonionic CTMAB-TX100and carbon-anionic CTMAB-SDS were used for preparationof modified bentonite. Adsorption performance and effects of different factors of organicpollutants and heavy metals on modified bentonite were investigated, and the changes ofthe structure of modified bentonite between layers were also discussed by the structurecharacterization. The mian contents and results are summarized as follows:1. The results from infrared spectrum and XRD show that CTMAB, TMAB, L-CsyH, CTMAB-TX100and CTMAB-SDS have been intercalated in the layer of bentonite,respectively, and organic bentonite was obtained.2. The adsorption of bisphenol E on CTMAB bentonite and TMAB bentonite, anduranium on L-CsyH bentonite agreed very well with the Langmuir isotherm model,however, the adsorption of atrazine on C-TX bentonite and C-S bentonite agreed verywell with the Freundlich isotherm model. Through the calculation of the thermodynamicparameters, All the adsorption process are exothermic reaction except the adsorptionprocess of uranium on L-CsyH bentonite.3. The adsorption equilibrium of bisphenol E on CTMAB bentonite and TMABbentonite were reahed within90min and60min. The adsorption equilibrium of atrazineon C-TX bentonite and C-S bentonite were reahed within6h and8h. The adsorptionequilibrium of uranium on L-CsyH bentonite was reahed within100min. All theadsorption reactions followed the pseudo-second-order kinetic model. Adsoprtion rateconstant of bisphenol E on CTMAB and TMAB modified bentonite was0.00193，0.00378 g mg-1min-1, respectively. Adsoprtion rate constant of atrazine on C-TX and C-S modifiedbentonite was0.000156,0.000135g mg-1min-1, respectively. Adsoprtion rate constant ofuranium on L-CsyH modified bentonite was0.00179g mg-1.4. The adsorption performance of pullutants on modified bentonite was better thanon original bentonite. The maximum adsorption capacity of bisphenol E on CTMABbentonite and TMAB bentonite was75.76mg/g and8.77mg/g, respectively. Themaximum adsorption capacity of uranium on L-CsyH bentonite was39.06mg/g. Theadsorption constant of atrazine on C-TX bentonite and C-S bentonite were1.9137and1.2898, respectively.5. The adsorption performance of pollutants on modified bentonite was related totemperature, pH value, the initial concentration of pollutants and dosage of modifiedbentonite. Adsorption capacity of bisphenol E on CTMAB, TMAB modified bentoniteand atrazine on C-TX, C-S modified bentonite decreased with increasing temperature,however, the adsorption capacity of uranium on L-CsyH modified bentonite increasedwith increasing temperature. Adsorption capacity of bisphenol E on CTMAB, TMABmodified bentonite increased with increasing pH, adsorption capacity of atrazine on C-TX, C-S modified bentonite decreased with increasing pH, adsorption capacity ofuranium on L-CsyH modified bentonite firstly increased and then decreased withincreasing pH. With the increase of the initial concentration of pollutants, the adsorptioncapacity would gradually increase. The increase of the dosage of modified bentoniteresulted in decreasing of adsorption capacity and increasing of removal efficiecy.